riscv/qemu - qemu - Gitea: Git with a cup of tea

Author	SHA1	Message	Date
Paolo Bonzini	ba773aded3	block: rename block/aio.h to qemu/aio.h AioContexts are used as a generic event loop even outside the block layer; move the header file out of block/ just like the implementation is in util/. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>	8 months ago
Paolo Bonzini	5f50be9b58	async: the main AioContext is only "current" if under the BQL If we want to wake up a coroutine from a worker thread, aio_co_wake() currently does not work. In that scenario, aio_co_wake() calls aio_co_enter(), but there is no current AioContext and therefore qemu_get_current_aio_context() returns the main thread. aio_co_wake() then attempts to call aio_context_acquire() instead of going through aio_co_schedule(). The default case of qemu_get_current_aio_context() was added to cover synchronous I/O started from the vCPU thread, but the main and vCPU threads are quite different. The main thread is an I/O thread itself, only running a more complicated event loop; the vCPU thread instead is essentially a worker thread that occasionally calls qemu_mutex_lock_iothread(). It is only in those critical sections that it acts as if it were the home thread of the main AioContext. Therefore, this patch detaches qemu_get_current_aio_context() from iothreads, which is a useless complication. The AioContext pointer is stored directly in the thread-local variable, including for the main loop. Worker threads (including vCPU threads) optionally behave as temporary home threads if they have taken the big QEMU lock, but if that is not the case they will always schedule coroutines on remote threads via aio_co_schedule(). With this change, the stub qemu_mutex_iothread_locked() must be changed from true to false. The previous value of true was needed because the main thread did not have an AioContext in the thread-local variable, but now it does have one. Reported-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20210609122234.544153-1-pbonzini@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Tested-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> [eblake: tweak commit message per Vladimir's review] Signed-off-by: Eric Blake <eblake@redhat.com>	5 years ago
Thomas Huth	da668aa15b	tests: Move unit tests into a separate directory The main tests directory still looks very crowded, and it's not clear which files are part of a unit tests and which belong to a different test subsystem. Let's clean up the mess and move the unit tests to a separate directory. Message-Id: <20210310063314.1049838-1-thuth@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com>	5 years ago
Stefan Hajnoczi	d73415a315	qemu/atomic.h: rename atomic_ to qatomic_ clang's C11 atomic_fetch_() functions only take a C11 atomic type pointer argument. QEMU uses direct types (int, etc) and this causes a compiler error when a QEMU code calls these functions in a source file that also included <stdatomic.h> via a system header file: $ CC=clang CXX=clang++ ./configure ... && make ../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int ' invalid) Avoid using atomic_*() names in QEMU's atomic.h since that namespace is used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h and <stdatomic.h> can co-exist. I checked /usr/include on my machine and searched GitHub for existing "qatomic_" users but there seem to be none. This patch was generated using: $ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h \| \ sort -u >/tmp/changed_identifiers $ for identifier in $(</tmp/changed_identifiers); do sed -i "s%\<$identifier\>%q$identifier%g" \ $(git grep -I -l "\<$identifier\>") done I manually fixed line-wrap issues and misaligned rST tables. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20200923105646.47864-1-stefanha@redhat.com>	6 years ago
Peter Maydell	0cb0406172	tests/iothread: Always connect iothread GSource to a GMainContext On older versions of glib (anything prior to glib commit 0f056ebe from May 2019), the implementation of g_source_ref() and g_source_unref() is not threadsafe for a GSource which is not attached to a GMainContext. QEMU's real iothread.c implementation always attaches its iothread->ctx's GSource to a GMainContext created for that iothread, so it is OK, but the simple test framework implementation in tests/iothread.c was not doing this. This was causing intermittent assertion failures in the test-aio-multithread subtest "/aio/multi/mutex/contended" test on the BSD hosts. (It's unclear why only BSD seems to have been affected -- perhaps a combination of the specific glib version being used in the VMs and their happening to run on a host with a lot of CPUs). Borrow the iothread_init_gcontext() from the real iothread.c and add the corresponding cleanup code and the calls to g_main_context_push/pop_thread_default() so we actually use the GMainContext we create. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Peter Xu <peterx@redhat.com> Message-id: 20200106144552.7205-1-peter.maydell@linaro.org	7 years ago
Stefan Hajnoczi	69de48445a	test-bdrv-drain: fix iothread_join() hang tests/test-bdrv-drain can hang in tests/iothread.c:iothread_run(): while (!atomic_read(&iothread->stopping)) { aio_poll(iothread->ctx, true); } The iothread_join() function works as follows: void iothread_join(IOThread *iothread) { iothread->stopping = true; aio_notify(iothread->ctx); qemu_thread_join(&iothread->thread); If iothread_run() checks iothread->stopping before the iothread_join() thread sets stopping to true, then aio_notify() may be optimized away and iothread_run() hangs forever in aio_poll(). The correct way to change iothread->stopping is from a BH that executes within iothread_run(). This ensures that iothread->stopping is checked after we set it to true. This was already fixed for ./iothread.c (note this is a different source file!) by commit `2362a28ea1` ("iothread: fix iothread_stop() race condition"), but not for tests/iothread.c. Fixes: `0c330a734b` ("aio: introduce aio_co_schedule and aio_co_wake") Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> Message-Id: <20191003100103.331-1-stefanha@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>	7 years ago
Paolo Bonzini	0c330a734b	aio: introduce aio_co_schedule and aio_co_wake aio_co_wake provides the infrastructure to start a coroutine on a "home" AioContext. It will be used by CoMutex and CoQueue, so that coroutines don't jump from one context to another when they go to sleep on a mutex or waitqueue. However, it can also be used as a more efficient alternative to one-shot bottom halves, and saves the effort of tracking which AioContext a coroutine is running on. aio_co_schedule is the part of aio_co_wake that starts a coroutine on a remove AioContext, but it is also useful to implement e.g. bdrv_set_aio_context callbacks. The implementation of aio_co_schedule is based on a lock-free multiple-producer, single-consumer queue. The multiple producers use cmpxchg to add to a LIFO stack. The consumer (a per-AioContext bottom half) grabs all items added so far, inverts the list to make it FIFO, and goes through it one item at a time until it's empty. The data structure was inspired by OSv, which uses it in the very code we'll "port" to QEMU for the thread-safe CoMutex. Most of the new code is really tests. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 20170213135235.12274-3-pbonzini@redhat.com Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>	10 years ago